add windows config test for config_symlink_home_no_duplicate_load

Author: fahdfady

tests/testsuite/config.rs

@@ -2596,8 +2596,13 @@ fn config_symlink_home_no_duplicate_load() {
     // already in the config search path, the config file is not loaded twice.
 
     use cargo_test_support::basic_manifest;
+
+    #[cfg(unix)]
     use std::os::unix::fs::symlink;
 
+    #[cfg(windows)]
+    use std::os::windows::fs::symlink_dir as symlink;
+
     let p = project()
         .file("Cargo.toml", &basic_manifest("foo", "0.1.0"))
         .file("src/lib.rs", "")